Oil and gas well perforating methods and apparatus



Aug. 12, 1958 M, P. LEBOURG 2,846,943

OIL AND GAS WELL PERFQRATING METHODS AND APPARATUS Filed June 1'7, 19532 Sheets-Sheet 1 FIG.2.

INVENTOR. MAURICE P; LEBOURG BY We! W /JIA HIS ATTORNEYS.

Aug. 12, 1958 M. PQLEBOURG 2,846,943

011. AND GAS WELL PERFORATING METHODS AND APPARATUS Filed June 17, 19532 Sheets-Sheet 2 INVENTOR. MAURICE P. LEBOURG WWW/[MW H IS ATTORNEYS.

2,846,948 Patented Aug. '12, 1958 OIL AND GAS WELL PERFORATIN G METHODSAND APPARATUS Maurice P. Lehourg, Houston, Tex., assignor, by mesneassignments, to Borg-Warner Corporation, Chicago, lll., a corporation ofIllinois Application June 17, 1953, Serial No; 362,213

Claims. (Cl. 102-21) This invention relates to methodsv and .apparatusfor perforating with shaped explosive charges a pluralityof verticallyspaced earth formations traversed .by a bore hole and more particularlyto perforation of such formations after the bore hole has been cased,production equipment has been placed at the surface and tubing has beenset in the cased bore hole.

It has become common field practice to employ the well completionmethods and apparatus disclosed in copending application Serial No.209,598, filed February6, 1951, by H. S. Robertson, for"Method andApparatus for Perforating Well Casing and the Like, and described in anarticle entitled A Method of Perforating Casing Below Tubing, by-M.PuLebourg and G. R. Hodgson, at page 303, vol. 195 (1952), PetroleumTransactions, AIME. When these practices are followed, productionequipment may be placed at the surface and tubing lowered and set in thewell'prior to perforating, thus simplifying well completion.

In some cases, it is desirable to vobtain production simultaneously fromtwo vertically separated formations in the well. However, the well maybe under high pressure from the fluid in thefirst formation afterperforation in accordance with the aforementioned methods and apparatus.As a result, perforation of the second formation in accordance with suchmethods and apparatus may be more difiicult and somewhat more hazardous.

Accordingly, it is an object of the present invention to provide new andimproved methods and apparatus for perforating with shaped explosivecharges, in one operation, a plurality of vertically spaced earthformations with production equipment placed at the surface and tubinglowered into the well.

Another object of-the invention-is to provide novel methods and meanswhereby a'plurality of vertically spaced earth formations may beseparately perforated without the necessity for lowering additionalequipment in the well after one of such formations has been perforated.

A further object ofthe-pre sent invention is to provide means forelectrically coupling components of equipment in a bore hole by means ofremote surface apparatus.

These and other objects of the invention are ,accotn plished bydisposingfirst 'shapedjexplosive charge perforating means at the lowerend of the tubing opposite the upper of two formations of interest suchthat the open end of the tubing is free and unobstructed. Second shapedexplosive charge perforating means is lowered through the tubing to thelevel of the lower of the two formations and is used to perforate thelower formation. The second perforating means includes means which,after perforation of the lower formation, is adapted to be positioned inthe vicinity of the first perforating means whereit acts upon means inthe first perforating-apparatus to cause detonation of the latter. Moreparticularly, the first perforating apparatus may have an electricaldetonating circuit including a winding in-which voltage is adapted to beinduced from a suitably energized winding forming part. of .the secondperforating apparatus, when the two are in inductive relation.

These and further objectsand advantages of the inven- I tion.'will bemore fully understood from the following description of a representativeembodiment, read with reference to the accompanying drawings,.in which:

Fig. l is a view in longitudinal section of a well which is undercompletion .in accordance with the present invention;

Fig.2 is a view, partially in longitudinal section of the lower end .ofthe tubing. and the shaped explosive charge perforating apparatussecured thereto;

Fig. 3 illustrates in diagrammatic form the components of a typicalcircuit that may be employed to discharge the shaped explosive chargeperforating apparatus mounted. at the lower end, of the tubing; and

Fig. 4 is aschematic diagram of an equivalent circuit of the dischargingcircuit of Fig. 3 when the several components thereof are in the firingposition.

Examining the invention in detail with particular reference to 'Fig. 1,a bore hole 10 has been completed in accordance with the procedureoutlined in the aforementioned Robertson application and publication.Set in a well 10 is a casing 11 which traverses a plurality ofpotentially productive formations 12 and 13 vertically separated by theformation 14. The usual production equipment, which is not shown forsimplicity, is placed at the .surface of the well, and the tubing 15 isset with the aid of a conventional packer 17 so that its lower end 16 isimmediately above the upper formation 12. Attached to the lower end ofthe tubing 16 is a firing nipple 18, to be described in greater detailhereinafter; The hollow interior of the tubing 15 communicates with anopening 19 in the nipple 18 whereby the tubing is, in effect,open'ended. A'first shaped explosive charge perforating device 20 isattached to the nipple 18 by a detonating unit 29. The perforatingdevice 20 is offset from the opening 19 and is positioned opposite theformation'12,-as shown-in Fig. 1. I

vThe perforating device 20 preferably comprises a plurality of shapedexplosive charges in an expendablehous ing as'disclosed in theaforementioned Robertson application, for example, the detonatingprimacord fuse for the charges terminating in an electrical blasting cap30 in the detonatingunit 29. The blasting cap 30 may have one terminalconnected to ground and another terminal connected to acontact 31.Placed in the firing nipple 18, offset from the opening 19, is a coil 25Wound on a magnetic core '32 placed longitudinally between twoannula'rpmagnetic pole pieces 26 and 27 having openings 34 and 35 formedtherein registering with the opening 19. One terminal-of the coil 25iselectrically connected to the contact 31, and the other terminal 33 ofthe coil25' is grounded, as shown in greater detail in Fig. 3.

For perforation of the lower formation 13, an expendable shapedexplosive charge perforating device 21, preferably-of the type disclosedin the aforementioned Robertson application, is adapted to be loweredthrough the tubing 15 and the nipple 18 to a position opposite theformation 13 by means of a conventional cable 22 which includes anelectrical conductor 43. The perforatingdevice 21 preferably containsthe modifications disclosed inthe copending application Serial No.322,017, filed November 22, 1952, by G. R. Hodgson for Expendable ShapedExplosive Charge WellCasing Perforating Apparatus, and 'in applicationSerial No. 322,070, filed November 22, 1952, by J. M. Bricaud for BoreHole Detecting Circuit and Bore Hole Firing Circuit Utilizing a CommonTransmission Channel, n0W-U. S. Patent No. 2,732,518, issued January 24,

1956. Between the perforating device 21 and the cable 22 is aconventional casing collar locator 23, which may be of the typedisclosed in U. S. Patent No. 2,558,- 427 to H. C. Fagan, and mechanism24 (Fig. 3) for firing the perforating device 20. The firing mechanism24 may comprise a coil 36 wound on a magnetic core 37 terminating incylindrical pole pieces 38 and 39. The spacing between the pole pieces38 and 39 is preferably the same as the spacing between the pole pieces26 and 27. An appropriate A. C. source 40 at the surface selectivelyenergizes the winding 36 through a switch 42, conductor 43 in the cable22, and a ground return, as shown schematically in Figs. 3 and 4.

In a representative operation, the perforating device 21 is lowered to aposition opposite the formation 13 as determined by the casing collarlocator 23 (Fig. 1). Setting off the perforating device 21 by closingthe switch 42 results in the perforation of the formation 13 and theseparation and dropping of the perforating device 21 from the headassembly including the casing collar locator 23 and the firing mechanism24, as disclosed in the aforementioned Robertson and Hodgsonapplications. In this manner, production of the formation 13 into thebore hole is started. The firing mechanism 24 and the casing collarlocator 23 are then raised until the former is in juxtaposition to thewinding 25 with the pole pieces 38, 39 and 26, 27, respectively, inalignment, as accurately determined by the casing collar locator 23.

As can be seen in Fig. 4, when the firing mechanism is located in theposition described above, the coil 36 comprises, in eifect, the primarywinding of a transformer, the coil 25 serving as a secondary winding.Close coupling between these coils will be provided in view of themagnetic path 41 provided by the core 37, the adjacent pole pieces 38and 26, the core 32, and the adjacent pole pieces 27 and 39. The switch42 is again closed, energizing the coil 36, resulting in the inductionof an A. C. potential in the coil 25 and current flow through thecontact 31 to the blasting cap 30. The subsequent detonation of theshaped charges in the perforating device 20 perforates the formation 12,resulting in production into the bore hole 10 therefrom.

The casing collar locator 23 and the firing mechanism 24 may then bewithdrawn from the well through the tubing and the well placed onproduction from both the formations 12 and 13.

Accordingly, it can be seen that novel and highly effective methods andapparatus are provided for perforating in one operation a plurality ofseparate formations traversed by a well after tubing has been settherein.

It should be understood that the methods and apparatus described areillustrative only and modifications may be made thereto. For example,other suitable shaped explosive charge perforating apparatus may besubstituted for the specific shaped charge devices described above.Numerous other modifications within the scope of this invention willsuggest themselves to those skilled in the art. Therefore, theembodiments described above and shown in the drawing are not to beregarded as limiting the scope of the appended claims.

I claim:

1. In a method for initiating operation of apparatus for use in a wellhaving a casing therein, the steps of setting tubing in the well withthe lower open end thereof at a selected level in the Well, disposing atthe lower end of said tubing without substantially obstructing theopening therein a first shaped explosive charge Well casing perforatingdevice including excitable operation initiating means, lowering throughthe tubing a second shaped explosive charge well casing perforatingdevice including means capable of exciting said operation initiatingmeans, causing said second well casing perforating device to perforatethe casing and earth formation at a given level in the well below saidfirst casing perforating device, positioning the exciting means of saidsecond well casing perforating device in exciting relation to said firstwell casing perforating device, and causing the exciting means of saidsecond well casing perforating device to excite the operation initiatingmeans of said first well casing perforating device to initiate operationof the same.

2. In a method for obtaining production from a plurality of earthformations traversed by a bore hole having a casing therein, the stepsof providing well tubing having secured at the lower open end thereof inoffset relation to the longitudinal tubing axis and withoutsubstantially obstructing the opening therein a first shaped explosivecharge well casing perforating device including excitable operationinitiating means, setting said tubing in the well with said first wellcasing perforating device opposite one of said formations, loweringthrough the tubing a second shaped explosive charge Well casingperforating device including means capable of exciting said operationinitiating means, causing said second casing perforating device first toperforate the well casing and earth formation at a level below the lowerend of the tubing, positioning the exciting means of said second casingperforating device in exciting relation to the operation initiatingmeans of said first casing perforating device, and causing said excitingmeans to excite said operation initiating means to initiate operaton ofsaid first well casing perforating device.

3. In a method for obtaining production from a plurality of earthformations traversed by a bore hole having a casing therein, the stepsof providing well tubing having secured at the lower open end thereof inofiset relation to the longitudinal tubing axis and withoutsubstantially obstructing the opening therein a first shaped explosivecharge well casing perforating device including first inductance coilmeansfor generating a voltage for the firing circuit thereof, settingsaid tubing in the well with said first well casing perforating deviceopposite one of said for mations, lowering through the tubing a secondshaped explosive charge well casing perforating device including secondinductance coil means adapted to be energized to excite the inductancecoil means of said first well casing perforating device, causing saidsecond well casing perforating device first to perforate the well casingand earth formation at a given level below the lower end of the tubing,positioning the inductance coil means of said second well casingperforating device in exciting relation to the inductance coil means ofsaid first well casing perforating device, and energizing said secondinductance coil means to induce a voltage in said first inductance coilmeans to initiate operation of said first well casing perforatingdevice.

4. In apparatus for use in a well, the combination of a member adaptedto be mounted on the lower end of an open string of well tubing andhaving an opening extending longitudinally therethrough, a shapedexplosive charge well casing perforating device mounted on said memberoffset from the longitudinal axis thereof so as not to obstruct theopening therein, an operating circuit for said perforating device andincluding inductance means in said member in which a voltage is adaptedto be induced when exciting means is positioned in said opening, a wellequipment component mounted for move ment through said well tubing andout of the lower end thereof, said well equipment component beingcontrollable from the surface for performing an operation at a selectedlevel in the well below said tubing lower end, and magnetizable excitingmeans mounted in fixed relation to said well equipment component forinducing a voltage in said inductance means when disposed in inductiverelation thereto, thereby to initiate operation of said perforatingdevice.

5. In apparatus for use in a well, the combination of a member adaptedto be mounted on the lower end of an open string of well tubing andhaving an opening extending longitudinally therethrough, a first shapedexplosive charge well easing perforating device mounted on said memberofiset from the longitudinal axis thereof so as not to obstruct theopening therein, an operating circuit for said perforating device andincluding inductance means in said member in which a voltage is adaptedto be induced when exciting means is positioned in said opening, asecond shaped explosive charge well casing perforating device mountedfor movement through said well tubing, and magnetizable exciting meansmounted in fixed relation to said second casing perforating device forinducing a voltage in said inductance means when disposed in in- Gductive relation thereto, thereby to initiate operation of said firstperforating device.

References Cited in the file of this patent UNITED STATES PATENTS1,133,183 Reineke Mar. 23, 1915 2,058,287 Anderson Oct. 20, 19362,120,615 King June 14, 1938 2,543,814 Thompson et al. Mar. 6, 19512,621,895 Toelke Dec. 16, 1952 2,640,417 Bjork et al. June 2, 19532,703,053 Castel Mar. 1, 1955

